N = int(input())
s = input()
num_R = s.count('R')
print(s[:num_R].count('W')) N = int(input()) N int(input()) int input() input s = input() s input() input num_R = s.count('R') num_R s.count('R') s.count s count 'R' print(s[:num_R].count('W')) print s[:num_R].count('W') [:num_R].count [:num_R] s :num_R num_R count 'W' s = input() input() s N = int(input()) int(input()) N num_R = s.count('R') s.count('R') num_R
N = int(input())
s = input()
num_R = s.count('R')
print(s[:num_R].count('W'))